If you have been using the XML and Atom plugins for Grouper Evolution to convert Atom feeds to RSS, and it sometimes works, but you sometimes get errors, it may be caused by the character encoding of the Atom feed. To check, load the Atom feed in your web browser, view the source, and take a look at the first line. It will probably look something like this:
<?xml version="1.0" charset="UTF-8" ?>
If instead of "UTF-8", it says "ISO-8859-1" or "US-ASCII", then this is not the source of the problem. In fact, "ISO-8859-any number" shouldn't cause errors, though some characters may display incorrectly. If the charset is anything else, for example, "windows-1252", then this probably is the source of the problem.
The problem is that, while windows-1252 is almost
identical to ISO-8859-1, it contains a few additional characters like smart quotes, etc. When the feed doesn't contain any of those characters, Grouper will work fine. But whenever one of those characters appears, there will be an XML parsing error. The reason for this is that PHP's XML parser only supports three character sets: UTF-8, ISO-8859-1 and US-ASCII.
If the Atom feed is under your control, for example, if it's from your own Blogger blog, then you may be able to solve the problem by changing the character encoding of the feed. I'd recommend using UTF-8, since it will support pretty much any character you might ever want to display--that's why it's the default encoding for XML files. In Blogger, you can change the encoding by clicking the "Settings" tab, clicking "Formatting" under the tabs, finding the Encoding popup, and changing it's value.